Thickening of solvent explosives systems

ABSTRACT

A process is disclosed for the thickening of hydrocarbon oil slurries of ammonium nitrate with a latex of an elastomer which is inverted into the nitrate slurry.

United States Patent [1 1 Du brow i THICKENING OF SOLVENT EXPLOSIVES SYSTEMS [75] Inventor: Paul L. Dubrowt Chicago. lll.

[73] Assignee: Nalco Chemical Company. Oak

Brook, Ill.

22] Filed: June 21. 1974 [2!] Appl. N0.;4s1,717

[56] References Cited UNITED STATES PATENTS 3.509.243 4/1970 Moore 149/60 X Nov. 11, 1975 1741.8. 6/1973 Brennan 149/60 X Primary Ev\'aminerStephen .I. Lechert. Jr. Attorney. Agent, or Firm-lohn G. Premo; Robert A Miller {5 7] ABSTRACT A process is disclosed for the thickening of hydrocarbon oil slurries of ammonium nitrate with a latex of an elastomer which is inverted into the nitrate slurry.

5 Claims, N0 Drawings This invention relates to a new and improved method for the thickening of hydrocarbon oil slurries of ammoniur'npitrate explosives, through the use of a latex of an ela'sto'mer. ln the practice ofthis invention, a latex containing elastomer is added to a hydrocarbon oil slurry of ammonium nitrate. Through the use of a surfactant, preferably pil soluble and of a high HLB value, the latex is invertedcaus'ing the polymer contained in it to soiub li ze into the hydrocarbon slurry and give a thickenirigefiectij UL'SI-Pat. 3,639,108 teaches the thickening of gasoline with latex compositions. It has been long kn'own'in' the art that the addition of an oil soluble polymeric composition will increase the viscosity, and cause a thickening of the solvent in which it is placed.

Howeventhepolymer so used has been in inconvenient forms,'either solid material which takes long dissolution times before use is practical, or as dilute solutions of'thepolymer of 'high viscosity, which due to their low .solids content make shipping uneconomical.

: I The use .of hydrocarbon oil slurries of ammonium nitrate explosives is well known in the art. it is common practice to use these slurries in a gel fon'n or at least substantially thickened in order that they retain their shape for a temporary period of time. It would be an advantage if the hydrocarbon oil slurry of ammonium nitrate could be prepared close to where it is used, quickly, and with simple apparatus.

The method of this invention, involves an improved method for the thickening of hydrocarbon oil slurries of ammonium nitrate explosives. The method of this invention involves adding to a hydrocarbon oil slurry of ammonium nitrate explosives a latex of an elastomer, followed by inverting the latex into the hydrocarbon oil slurry. The method of this invention, provides to the art a new and improved rapid method for thickening hydrocarbon oil slurries of ammonium nitrate explosives in a short period of time, as well as providing a more economical means.

OBJ ECT S It is therefore an object of this invention to provide an improved method for thickening hydrocarbon oil slurries of ammonium nitrate explosives.

Another object of this invention is to provide a method for thickening hydrocarbon oil slurries of ammonium nitrate explosives by inverting a latex of a polymer selected from the group consisting of cis-l-4- polyisoprene and polyisobutylene into a hydrocarbon oil slurry of ammonium nitrate.

Other objects will appear hereinafter.

THE INVENTION This invention involves a method for thickening hydrocarbon oil slurries of ammonium nitrate explosives by adding to such slurry a latex containing a finely divided polymer of either cis-lA-polyisoprene and/or polyisobutylene, followed by inverting the polymer so as to make it soluble in the oil phase with the use of an oil soluble high HLB surfactant.

This invention involves the use of either natural or synthetic latices of elastomers. Specifically, the elastomers involved include cis-l-4-polyisoprene and polyisobutylene. Latices of these polymers are well known in the art and typically contain 5 to% by weight polymer, 25 to 75% by weight water, and .01 to 5% by weight of a surfactant which is water-soluble. For the purposes of my invention, it is desirable to use a latex containing as much polymer by weight as possible while still maintaining a stable emulsion. In the practice of my invention, the preferred surfactants used to invert the emulsion are those which areoil soluble and have high HLB values. The surfactant chosen to invert the polymer must be soluble in the particular oil that is used in making the hydrocarbon oil slurry of ammonium nitrate which is desired to be thickened. Suitable emulsifiers include diesters of polyethyleneglycol, with molecular weights of between 200 to 600, with fatty acids containing '14 to 18 carbon atoms. Specifically,

the preferred. emulsifier is polyethyleneglycol of a molecular weight of about 400 which has been diesterified with oleic acid. It is important to note however, that the choice of a surfactant for inverting the emulsion will dependon several characteristics, including: the emulsifier used to produce the polymer latex; other organic additives present in the hydrocarbon oil slurry of ammonium nitrate; and the characteristics of the polymer used. Based on this, it is advisable to run small-scale tests before chosing' a surfactant to be used in larger scale batches.

The HLB system, hydrophile-lipophile balance formulated by Atlas Industries is a mechanism by which the hydrophobicity and lipophilicity of surfactants are measured, Typically, latices of elastomers are made with surfactants having a low HLB value (0 to 7). In the choice of an emulsifier to be used for inverting the latex, a surfactant with an l-lLB value opposite the one used to form the original polymer latex should be used.

The oil soluble surfactant used for inverting the polymer latex may be added directly to the latex, or to the hydrocarbon oil slurry of ammonium nitrate either before or after the latex of the polymer is added. Typically, from .01 to 10% by weight of the surfactant used for inverting is added based on the polymer present in the latex. The most preferred amount of surfactant to be added is from .01 to 5% of the weight based on the polymer contained in the latex. Typically, the amount of polymer used will depend upon the amount of hydrocarbon or oil solvent present in the ammonium nitrate slurry. For best results, I believe that the percent polymer should be greater that 0.1% based on the weight of the total slurry. However, due to characteristics of these solutions and different ways of manufacturing the ammonium nitrate slurries, the level of polymer will vary on a case-by-case basis. The slurries of ammonium nitrate used in this invention may contain either granuiar powdered or prilled ammonium nitrate. Since the form of ammonium nitrate used will vary the consistancy of the slurry, more polymer may be needed in cases where granular or prilled ammonium nitrate is used rather than powdered ammonium nitrate. in some cases, using extremely concentrated ammonium nitrate slurries, the polymer content necessary to gel the slurry may be under 3% of the total hydrocarbon or oil solvent. In most cases, however, a level greater than 3% is preferred, and this amount may be increased to as high as 20% for slurries containing small amounts of ammonium nitrate.

In order to prepare a thickened sample of an organic solvent based explosive, the following are procedures that would be followed:

EXAMPLE 1 To a 1,000 g. sample of a 75% by weight NH NO slurry in No. 2 fuel oil would be added 1.0 g. of polyethyleneglycol (400) dioleate with agitation. Immediately thereafter 60.0g. of a 50% natural rubber latex would be added to the resulting slurry with agitation. The mixture should thicken within 5 minutes.

EXAMPLE 2 polyisobutylene to provide a polymer concentration in the hydrocarbon oil slurry of NH NO from .01 to 20% by weight; and then.

B. inverting said latex containing the polymer into the hydrocarbon oil slurry of ammonium nitrate by means of an oil soluble surfactant having a high hydrophile-lipophile balance value whereby the polymer contained within the latex is solubilized and the hydrocarbon oil slurry of ammonium nitrate is thickened.

2. The process of claim 1 wherein the latex consists of from 5 to by weight polymer, from 25 to 75% by weight water and from .01 to 5% by weight of a water-soluble surfactant having a low hydrophilelipophile balance value.

3. The process of claim 1 wherein the latex is a natural rubber latex.

4. The process of claim 1 wherein the latex contains from .01 to 10% by weight of an oil soluble surfactant having a high hydrophile-lipophile balance value, based on the polymer contained in the latex.

5. The process of claim 1 wherein an oil soluble surfactant having a high hydrophile-lipophile balance value is added to the hydrocarbon oil slurry of NH.NO 

1. A PROCESS FOR THE THICKENING OF HYDROCARBON OIL SLURRIES OF AMMONIUM NITRITE EXPLOSIVES WHICH COMPRISES THE STEPS OF: A. ADDING TO A HYDROCARBON OIL SLURRY OF AMMONIUM NITRATE A LATEXT CONTAINING A POLYMER SELECTED FROM THE GROUP CONSISTING OF CIS-1-4-POLYISOPRENE AND POLISOBUTYLENE TO PROVIDE A POLYMER CONCENTRATION IN THE HYDROCARBON OIL SLURRY OF NH4NO3 FROM .01 TO 20% BY WEIGHT, AND THEN, B. INVERTING SAID LATEX CONTAINING THE POLYMER INTO THE HYDROCARBON OIL SLURRY OF AMMONIUM NITRITE BY MEANS OF AN OIL SOLUBLE SURFACANT HAVING A HIGH HYDROPHILE-LIPOPHILE BALANCE VALUE WHEREBY THE POLYMER CONTAINED WITHIN THE LATEX IS SOLUBILIZED AND THE HYDROCARBON OIL SLURRY OF AMMONIUM NITRITE IS THICKENED.
 2. The process of claim 1 wherein the latex consists of from 5 to 75% by weight polymer, from 25 to 75% by weight water and from .01 to 5% by weight of a water-soluble surfactant having a low hydrophile-lipophile balance value.
 3. The process of claim 1 wherein the latex is a natural rubber latex.
 4. The process of claim 1 wherein the latex contains from .01 to 10% by weight of an oil soluble surfactant having a high hydrophile-lipophile balance value, based on the polymer contained in the latex.
 5. The process of claim 1 wherein an oil soluble surfactant having a high hydrophile-lipophile balance value is added to the hydrocarbon oil slurry of NH4NO3. 